Posttraumatic Stress Disorder (PTSD) is an anxiety disorder than can develop after a person witnesses a traumatic event. A traumatic event can take many forms--a natural disaster, sexual abuse or a terrorist attack such as 9/11--but for veterans, PTSD is most often related to combat or military exposure.

In wars prior to Vietnam, the disorder was referred to as “shell shock” or “battle fatigue” and was not very well understood beyond the fact that it limited the soldier’s performance on the battlefield. Today, the disorder is more widely studied. We know that PTSD can lead to other mental health problems such as depression, social withdrawal and substance abuse.